Pearce Simpson CB manual wanted

Let me first congratulate you and your staff on your excel­lent magazine of which I have never missed a copy.

I have a problem that you or your readers may be able to help me with. I recently purchased an Hatadi Pearce Simpson UHF CB transceiver Model Leopard Mk2: SN301848 and requested from the supplier, Hatadi Electronics, a technical manual and circuit dia­gram. I received a reply from Brightpoint Aust. Pty Ltd telling me that they had taken over Hatadi and no longer had anything to do with CB radios and therefore were unable to help me.

Could anyone help me with these or an address of a Pearce Simpson agent (NZ or Australia) to whom I could write? Or perhaps someone could supply the manual and circuit diagram direct.

A. Plimley, 100 Parawai Road,
Thames, New Zealand.

"Mantel" vs "Mantle"

Thank you so much (once again) for providing us with a "real" Australian electronics magazine. It’s good to see that Jim Rowe and others have joined your team of authors.

Sorry to be a bit nit-picky but would you please tell Rodney Champness (in the nicest possible way, after a large thank-you for his articles on Vintage Radio) that the sort of radio he is referring to is spelled "mantel", not "mantle".

Like mantel clocks, they sit on a mantelpiece.

David Pulford,
Forestville, NSW.

Marconi signal generator on offer

I have an old Marconi AM Signal Generator, Type TF 801A/1, which covers from 10-310MHz at 75Ω, with a 100dB switched atten­uator, plus handbook.

Before I scrap this, I thought it might be of interest to a collector, avid shortwave listener or a vintage radio enthusiast. If it is, I will be happy for them to collect it from the address below.

M. Benyon, 61/27 Rangers Road,
Cremorne, NSW 2001.
Phone (02) 9953 5216.

In defence of DVD

I would like to come to the defence of DVD which has come in for a bagging in recent letters. In the letter by Brad Shear­gold (October 2001), he stated that his friend’s new Fujitsu monitor was 1.5m wide and running at 1,000,000 * 1,000,000 pixels in XVGA mode.

In the first case, the largest plasma display that Fujitsu make is the PDS4221/PDS4222 which is 1035mm wide with a screen width of 920mm and a pixel resolution of 1024 * 1024. I find it interesting that it was running in XVGA mode. Does this mean it was connected to a computer running with a DVD player? In that case, did the computer have a hardware or software decoder for the DVD signal, as software decompression does not produce any­where near the quality of a hardware decoder.

As for requiring a $US8000 to $US10,000 player to get a decent picture, I have a $329 Omni player that produces excellent picture quality on a standard 68cm TV – far in excess of that from VHS. Indeed the picture quality is that much better that my wife, who usually shakes her head at my ‘toys’, commented on the difference and allowed me to buy a new 5.1 sound system to complement the picture.

In the email by Simon Kareh (September 2001), he states that when he watched a movie in widescreen mode that the heads were cropped. I have a number of doubled-sided DVDs with one side in widescreen and the other in normal (or 4:3). Since his email, I have reviewed all these and in all cases the 4:3 picture re­moved the side part of the picture (ie, a narrower view) while in widescreen there was no such cropping.

The widescreen ratio is that which is seen at a movie thea­tre and I hear no complaint about heads being cropped. Addition­ally, PAL/SECAM DVD movies are encoded at 720 * 576 while NTSC are encoded at 720 * 480. So based on his 56% lines available, this would be 322 lines which is a significant improvement over VHS with 250.

John Richardson (October 2001) has missed an important point when he says that 44% of the bandwidth is taken up with the black bars. MPEG compression works by only recording those sec­tions of a picture that have changed from one frame to the next. So even if the black bars are transmitted they do not take up bandwith as there as been no change.

I have numerous friends with DVD players and all have agreed with my comment regarding quality. As far as owning DVD discs is concerned, at present I own approximately 180 compared to about seven VHS tapes. This clearly states my opinion on DVD.

Doug Palfreyman,
Quorrobolong, NSW.

DVD far superior to VHS

After reading the letters about DVD in the September and October issues, I felt compelled to provide my experiences in that direction. I have had a DVD player almost since they became available here. Having had three different units in that time, I can tell you that the quality of the picture does vary between the players. It is mostly in the set-up alternatives available but also in the design.

For example, the Toshiba allows selection of the 16:9 format for all DVDs that we have played whereas the new cheapie did not (that player has now been sold). To be sure, if the DVD is coded only in widescreen format, then there are scan lines at the top and bottom that are black - even in 16:9 mode. But there are about half as many as when (normal) 4:3 letterbox mode is selected.

Note that some DVDs do have dual coding which allows full vertical use of the screen but there seem to be less of these lately. The industry seems to want to put more "bonus material" on the DVD rather than provide alternative playback modes.

In all cases where we have compared the VHS and DVD ver­sions of a movie, the DVD, even in letterbox mode, was far supe­rior to two VHS machines. Our TV picture is two metres wide, from a video projector, using component video from the DVD and S-video from the VHS. Absolutely every defect in the TV picture is appar­ent in a picture that large. Our major source of complaint though is the wide variability of quality of picture from the free-to-air TV stations.

In particular, all stations have produced terrible outside broadcast pictures. The conversion used from digital to analog is also poor, with flicker and jerkiness in the rapidly changing parts of the picture. This same defect has also been noticed in normal definition digital mode from Digital TV.

We are now on our second projector, with each giving a slightly different picture, mostly due to the different type of projection. And while each had defects, such as a very slight shimmer in some parts of the picture on one, they both have given excellent results, with no line structure evident in either (due to line doubling).

On the sound side, there is no comparison between DVD and Hifi VHS. The 6 (or 5.1) channel digital bitstream from the DVD provides absolutely awesome sound, with the sub-woofer capable of shaking you in your seat and the multi-channels enveloping you in the action. The 2-channel Dolby encoded Hifi VHS does not come close. I have a Sony sound system than can fully decode all systems. There is far more "atmosphere" with the digital sound.

My conclusion is that not all players or TVs are equal and that you need to have the right equipment, properly set up, to get the best out of DVDs. The same would apply to digital TV since there are many stories coming out on the Internet about problems there. The providers of DVDs also need to supply them with selectable alternative coding for full screen .

Bruce Withey,
via email.

DVD misconceptions

On reading the October, 2001 Mailbag I was struck by letters from two readers who seem to have gotten "less-than-optimal" results from their DVD viewing, so I thought that I would throw in my two cents worth.

In regard to Brad Sheargold’s letter, first off, his friend has misquoted the resolution of his display to you. The most expensive Fujitsu model has approximately 1000 by 1000 pixels for a total area of one million pixels, not 1,000,000 by 1,000,000.

Secondly, you must realise that a plasma display has a lower contrast ratio and a smaller colour range than a normal TV which means that the picture will look washed-out and seem to miss detail in dark areas unless it is viewed under proper light­ing conditions. Low indirect lighting is the definite go and the poor colour range and bad lighting would explain the "256 colours" impression you were getting.

All TVs need to be properly adjusted to get a really good image, plasma sets even more so. Do not rely on the factory default settings to be optimal, especially sharpness which should be turned right down for viewing DVDs, and brightness which needs to be adjusted carefully to ensure a good picture.

As for the image "continually digitally raining"; I own over 200 disks and have never encountered this effect playing a DVD but it could be a video connection problem.

Lastly, I have a 7-year old 68cm Sony TV that cost $1500 and a 2-year old $1000 Toshiba DVD player that together deliver wonderful picture quality, so I have to say that spending $US8000 - $US10,000 is definitely not required. Until I saw my first proper HDTV transmission just over two weeks ago, the quality of the picture that I have been watching has been unsurpassed.

I would urge Mr Sheargold to go into a hifi store and look at DVD running on a properly set up CRT-based TV before becoming too disillusioned.

In regard then to Mr John Richard­son’s letter, where do I start?

When a DVD is encoded for a full-frame 4:3 ratio image, the resolution of the image is approximately 720 by 540 pixels (approximately 500 TV lines). When a DVD is encoded for an ana­morphic widescreen 16:9 ratio image, the resolution is 720 by 540 pixels. "How can they both be 720 x 540 when one is widescreen and the other not?"

The answer is that DVD encodes the widescreen picture information in a full frame without any black bars, making the vertical resolution a full 500 lines, not 281 lines as Mr Richardson claims. When the image is displayed on the 4:3 format TV, the image is either "compressed" into the centre of the screen as my TV does, or re-interpolated by the DVD player to fit the screen and the black bars added. On a widescreen TV, the image is displayed in its full 500-line glory; a tad better than VHS’ 220 lines.

As for FTA stations going to the trouble of encoding their transmissions between towers, it would seem to be very unlikely, especially since the black bars are left out of the encoding process. If they did however, you certainly would not be able to notice as analog TV is much lower resolution than MPEG2. Besides, if it’s a conspiracy to save bandwidth, who are they saving it for? It’s not like it hasn’t already been allocated to them, and nobody is receiving a secret channel!

By the way, it is important to understand the quantitative as well as qualitative differences between MPEG encoding and MPEG2 encoding. MPEG compression, as can be seen in computer video and low-quality VCD movie disks that are popular in Asia, is about one quarter the resolution and a tenth of the bandwidth of a MPEG2 compressed movie on DVD.

Mr Richardson said that DVD has not delivered on its prom­ises. I know of many disks that use multi-angle. Whether this is used for multiple camera angles or for some other purpose such as showing how a film is made is up to the director of the film. You can go out right now and find many disks with auto pan-and-scan encoding; I suggest "Galaxy Quest" or "Chicken Run" as exam­ples.

I’ll admit that while many disks will prevent you from jumping thought the copyright notices but you can easily skip around the disk once you’re in. However, if you think that VHS-quality sound is just as good as DTS or Dolby Digital, I would say that you just haven’t heard it yet or you need your ears checked.

When I first saw a DVD on a badly set up TV in a now-defunct electronics chain store, the quality was appalling. I almost gave up on the format then and there but since then I have seen and heard quality that far surpasses any other format.

Phil Harvey, Punchbowl, NSW.

Test equipment and parts on offer

I have been an electronic hobbyist since my teens and a professional electronics engineer since my mid-twenties. Now, I am getting beyond doing much "hobbying" and we are moving out of our house to a smaller unit.

I have a quantity of electronic components and test equipment (some commercial, some home-made). If anyone is interested in these items, I would be glad to send them a list, by email or mail, though email is better. I would only ask for a contribution to transport for many or large items, or where the recipient is far from Adelaide.

Ewart Jones, 15 Hurds Hill Drive,
Coromandel Valley, SA 5051. pejcoro@chariot.net.au